Refrigerating apparatus



Aug. 26, 1941. E. F. SMITH REFRIGEI RATING APPARATUS Filed March 9; 1959- 2 Sheets-Sheet l ATTORNEYS 1 ENTOR.

Aug 26, 1941. F, SMITH 2,253,657

' REFRIGERATING'APPARATUS Filed March 9, 1939' 2 Sheets-Sheet 2 S5 A w ATTORNEYS Patented'Aug. 2c, 1941 REFRIGERATINGI APPARATUS Emil Frank Smith, Chicago, Ill., assignor to Gen* eral Motors Corporation, Dayton, Ohio, a. corporation of Delaware Application March 9, 1939, Serial No. 260,786

4 Claims.

This invention relates to refrigerating apparatus and more particularly to means for indicating a loss of refrigerant from the system.

In large refrigerating systems a leak may cause a considerable loss of refrigerant. The refrigerants ordinarily used in such systems are rather expensive and if a leak is not discovered or isolated within a short time a considerable loss of refrigerant may occur. In some localities the code requires that'some sort of a safety device be used to indicate the loss of refrigerant. I 'flnd that the systems heretofore employed for. this purpose are either very expensive or they do not operate properly. For example, many of the more simple systems give an indication of loss of refrigerant when actually no loss has occurred.

It is an object of my invention to provide an improved simple refrigerant detecting system which, will indicate when a predetermined loss of refrigerant has occurred and which will not give false indications.

It is another object of my invention to provide an indicating device for indicating loss of refrigerant which is operative only when the system is in proper condition for making a test for the loss of refrigerant.

It is still another object of my invention to provide a system for indicating a loss of refrigerant which is controlled by a. timing device.

It is still another object of my invention to provide an indicating device which is operative only when the refrigerating system is idle.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a diagrammatic view of a large multiple air conditioning compression refrigerating system embodying one form of my invention;

Fig. 2 is a wiring diagram for the refrigerating system shown in Fig. 1, together with a wiring diagram of the indicating device for the system shown in Fig. 1;

Fig. 3 is a fragmentary view of the float controlled switch for the receiver;

Fig. 4 is an enlarged sectional view of the float controlled switch shown in Fig. 3; and

Fig. 5 is a view of the timing device for the indicating means.

Briefly, I have shown an air conditioning system in which each of the evaporating means is controlled by an individual thermostat controlling a solenoid valve in the liquid line of its evaporating means. The motor-compressor unit is controlled by a low pressure control switch. The receiver is provided with a float controlled switch which is energized only after all of the solenoid valves have been closed for a period sufficiently long that a' substantially fixed proportion of the refrigerant in the system has been transferred to the receiver. When the liquid level'within the receiver at that time is below a predetermined level the float controlled switch will be closed thereby causing theoperation of the signaling device. v

The refrigerating system Referring now to the drawings and more particularly to Fig. 1 there are shown air condition! ing units 20, 22 and 24 which are located within separate compartments 26, 28 and 30 These 'air conditioning units 20, 22 and 24 are provided with refrigerant evaporating means32, 34 and 36 which are provided with the usual thermostatic automatic expansion valves and in addition, the solenoid operated liquid line valves 38, 40 and 42 -whi'ch open when energized and close when deenergized. These solenoid valves 38, 40 and 42 are controlled by thermostat switches 44, 46 and 48 which are located within the rooms or chambers 26, 28 and 30. The outlet of each of these evaporating means is connected by a refrigerant conduit to a common suction conduit 50 which connects to the inlet of the compressor 52.

The compressor 52is driven by an electric motor 54 for withdrawing evaporated refrigerant from the evaporating means and compressing the refrigerant and forwarding the compressed refrigerant to the condenser 56 where the compressed refrigerant is liquefied and collected in a'receiver 58. From the receiver 58 the liquid refrigerant is forwarded through a common liquid line 60 to individual liquid lines connecting to the solenoid valves 38, 40 and 42 which control the supply of liquid to the evaporating means 32, 34 and 36. The operation of the motor-compressor unit 54 is controlled by a low pressure switch 62 having its bellows connected by a capillary tube to the common suction-conduit 50.

The float controlled switch The receiver 58 is providedwith a float controlled switch means of the type which is disclosed in Patent No. 2,067,638 to James R. Hornaday. Figs. 3 and 4 show a suilicient portion of this float controlled device to illustrate its operation. The receiver 58 has a cup-shaped member 84 sealed to the end wall 88. A fixed stud 88 mounted on the end of the cup 84 inside of the receiver 58 forms a pivot which carries a float member also located inside the receiver. The float member 10 is provided with U-shaped arms 1| and 12 which extend adjacent the walls of the cup member 84. These arm portions H and 12 are made of a magnetic'material, such as iron, while the cup-shaped member 84 is made of a non-magnetic material, such as brass. v

Within the cup member 84 is removably'positioned a float operated switch 80 comprising a cylindrical shell 18 of a non-magnetic material, such as brass, which is closed at its irmerend by an end plate 18. A U-shaped bracket 80 is secured to the end plate 18 and carries centrally of the shell an adjustable pivot 82. IA fixed pivot 84 is secured to the-central portion of the end'piate 18. Between the pivots 82 and 84 there is mounted a movable member comprising a hub 88 and a transverse bar 88 of magnetic material, such as iron. Preferably the bar 88 is permanently magnetized although if desired the portions H and 12 may be permanently magnetized. The hub 88 also carries an arm 80 upon which is mounted at one end a stud 82 which forms a movable contact member. The arm 80- at its opposite end is formed into an indicator pointer 94.

A flexible conductor 98 is connected to the bracket 80 and to the stud 82 to insure continuity of the electrical circuit. The bracket 80 also carries an insulated plate I00. The plate I00 in turn carries a fixed contact I02 which is positioned in the path of movement of the stud 82. The contact I02 is clamped to the plate I00 by .a screw I08. This screw I08 is connected by a conductor to the electrical terminal I08. The base I I0 is provided with an opening I I2 through which the pointer 94 may be viewed. The base H0 and the plate II4 are provided'with an in sulating bushing II8 through which the terminal I08 extends. The assembly comprising the end plate 18, the bracket 80, the plate I00 and their associated parts is secured in the shell 18 and the shell 18 is in turn secured to the plate ,4 by bolts and by the post I20.

In operation of the device the float 18 moves in response to changes in the liquid refrigerant level within the receiver 58 and carries with it the magnetic portions H and 12. The cross bar 88 is caused to follow the movement of the float 10 by magnetic attraction thus movi g the pointer 94 and .the movable contact 82 i response to changes in the liquid'level. When the float 10 has fallen'sufilciently the movable contact 82 will be carried into contact with the stationary contact I02 thus closing the float operated contacts. The plate H4 and the entire assembly withinthe cup 84 may be turned so as to change the level at which the contact 82 makes contact with'the contact I02. For this purpose a slot I28 is provided in the end plate II4 for limiting the movementof the end plate and a nut and stud I80 is provided for clamping the end plate I in the desired position.

The detecting system Referring now more particularly to the wiring diagram shown in Fig. 2, the? supply conductors which supply electricity to the entire system are "pressure controlcontacts 82. Also connected to designated'by the reference characters 282 and erated switch 2I0, which is closed when deenergized and opened when its solenoid is energized.

The solenoid operating the switch 2I0 is desi nated by the reference character 2I2 and this solenoid 2I2 is connected in parallel with the solenoid of the solenoid valve 88.v Both the solenoids 88 and 2I2 are connected in series with thermostat 44. The switch 2I0 is connected by the conductor 2 to a similar solenoid operating switch 2I8 having its solenoid 2I8 connected in series with the thermostat 48 and in parallel with the solenoid 40. The switch 2I8 is closed when deenergized and opened when energized. The switch 2I'8 is connected by the conductor 220 toa similar solenoid operated switch 222 having its operating solenoid 224 in parallel with the solenoid valve 42 and in series with the thermostat 48. Like the other solenoid switches the switch 222 is closed when deenergized and opened when energized. I

Thus all three switches are connected in series with each other and the switch 222 is connected by a conductor'.228 to one terminal oi. a time delay device 228. The conductor 208 is also connected by a conductor 280 to a second terminal of the time delay device 228. These two conductors 228 and 280 supply the electric energy necessary to start and operate the time delay device 228. In order to supply the electrical energy which is controlled by the float operated switch a conductor 282 is provided connecting the "conductor 208 directly to the float switch 80 and anotherconductor 284 is connected to one oi. the contacts operated by the time delay device 228. Also connected in series with the floatoperated switch 80 and the contacts operated by the time delay device 228 is a step-down door bell transformer 28-8 to which is connected a door bell 288 or other suitable signaling device, such as a lamp, which rings when the transformer 288 is energized by the closing of the circuit through the conductors 282 and 284, which includes the contacts 288, 210 and 212 operated by the time delay device 228 and the float switch 80.

Operation of the leak detecting system By this system the closing of any one of the thermostats 44, 48 and 48 prevents the energization of the time delay device since theclosing of any one of these thermostats will energize one oi. the solenoid switches 2n, 218 or m to open one of the switches 2I0, 2I8 or 222 which will prevent the supply of energy to the time delay device 228. As long. as no current is supplied to the time delay device 228, the contacts 288,

210 and 212 operated by the time delay device 228 will open and the transformer 288 cannot time delay device 228 will cause the closing of the contacts 268, 218 and 212 operated by the time delay device 228 after a definite period of time for which the time delay device 228 is set.

When these contacts 268, 218 and 212 are closed,

the energization of the transformer 236 will depend upon the liquid level within the receiver 58. The time delay device 228=is preferably set to close the contacts 268, 218 and 212 after a switch 68 will remain in open position and the Y transformer 236 will not be energized. If, how-' ever, the liquid level within the receiver 58 at this time has fallen to a predetermined low limit the contacts of the float operated switch 68' will be closed and the transformer 236 will be energized to cause the ringing of the bell 238 and for the lighting of one or more signal lamps.

The time delay mechanism It is not necessary that any particular form of time delay device be used, but forthe purpose of illustration I have shown one'particular form which is satisfactory for this purpose. In this form there is shown a self-starting synchronous motor 248 which is provided with a gear 242 meshing with an idler gear 244 to drive a larger gear 246 fixed to a rotatable shaft 248 which also carries a contact drum 258. This contact drum. 258 is fixed to the shaft 248 but is connected by a light coil spring 252 to an anchor 254. The position of the idler gear 244 is controlled by a solenoid 256. When the solenoid 256 is energized it will move the idler gear 244 into engagement with the gears 242 and 246 so that the motor 248 will slowly rotate the drum 258. When the sole- 3 I 'noid 256 is deenergized its retracting spring 258 will pull the idler gear 244 out of engagement with the drum gear 246' thereby permitting the spring 252 to immediately return the drum 258 to starting position. Thus any deenergization of the time delay device 228 at any time will return the drum 258 to its starting position thereby preventing the energization of the transformer 236 and the bell 238.

The contact drum 258 carries a contact portion 268 at one end which is adapted to make contact with the contacts 262 and 264 in order to close the circuit within the time delay device 228 to energize the motor 248 and the solenoid 256.

This contact portion-268, however, is provided with a gap 266 which, when the drum 258 is turned sufliciently far indicating the lapse of the predetermined delay period, will reach the contacts 262 and 264 and they will no longer be bridged by the contact portion 268. However, the

drum 258 also carries the contact 268 which is adapted to bridge the contacts 218 and 212 when the gap 266 reaches the contacts 262 and 264. It should be noted that when the gap 266 reaches contacts 262 and 264 that the motor 248 willbe deenergized to stop the rotation of the drum since the contacts 262 and 264 are connected directly in series with the motor 248; However, the

solenoid 256 is connected in parallel with the con-, tacts 262 and 264 so that it will remain energized 75 and prevent .the releasing of the drum 258. Therefore the drum will remain in this position with the contact 268 bridging the contacts 218 and 212 to permit the energization of the transformer 236 by the closingrof the float switch 68 as long as the refrigerating system is not in operation. However, as soon as the refrigerating system starts, the closing of any one of the thermostats will deenergize the time delay device thereby 'deenergizing the solenoid 256 to permit the spring 258 to pull the idler gear 244 out of engagement with the drum gear 246 to permit the drum 258 to return to its starting position under the influence of the spring 252.

. If desired the transformer. 236 may be caused to operate other signaling devices and the current flowing through the float control switch 68 .may be caused to operate solenoid valves or switches for shutting off. any portion of the refrigerating system or for preventing operation of the motor-compressor-unit. If desired an additional switch which is closed when the low pressure switch is open, may be connected'in the conductor 226 in series with the switches 2|8, 2l6 or 222. also, if desired, such a switch, which is opened when the switch 62 isclosed and which is closed when the switch 62 is open, may be substituted for" the three switches 2|8, 2 l6 and 222 in certain types of installation.

While the form of embodiment of the inven-.

tion as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coining within the scope of the claims which follow.

What is claimed is as follows:

1. Refrigerating apparatus including a cooling unit, circulating means for circulating a refrigerant medium through the cooling unit, means for controlling the circulation of refrigerant medium I through the cooling unit, means for indicating a a change in the quantity of the refrigerant medium for a period of time following the stopping of the circulation through the, cooling unit.

2. Refrigerating apparatus including a cooling erant medium through the cooling unit, means for controlling the circulation of refrigerant medium through the coolingunit, means for indicating a change in the quantity of therefrigerant medium in a portion of the apparatus, means for preventing the effective operation of the indicat ing means when crefrigerant medium circulates through the cooling unit, means for operating the circulating means until there is attained a predetermined condition of the refrigerant medium andtime delay means for delayin the effective operation of the indicating means for a period of time following the stopping of the circulation refrigerant within a portion of the system, means for individually rendering the evaporating means ineffective independently of .each other, and means for rendering the indicating means inoperative whenever any one of the evaporating means is eflective.

EMIL FRANK SMITH. 

